On 2020-09-04, at 22:24:56, Dan Greiner wrote: > ... > With the advent of z/Architecture, a similar means of problem-state linkage — > and AMODE switching — was needed, but now it had to accommodate three AMODEs. > Utilizing bit 63 of the instruction address (which, because instructions are > always on a halfword boundary, could never be used to address an instruction) > proved to be an interesting hack to accommodate the 64-bit AMODE. > However, I believe I see some conflict in that if a CSECT has AMODE 64 and a declared ENTRY to a data area, not executable code, on a even boundary, an ADCON referencing that will improperly have bit 63 set.
And how doe AMODE 64 code branch to an AMODE 31 CSECT? To an AMODE 24 CSECT? Can an initiator directly ATTACH an AMODE 64 program which expects a 144-byte save area? -- gil
